During our studies on breast diseases, the following biochemical values were measured: chlorine, sodium, potassium and albumin. We examined 153 syringe biopsies from women aged between 34 and 55 years, and an analysis of the above mentioned parameters enabled us to classify the breast cyst fluid into 2 groups: group I was definitely benign, while group II was calculated as having a risk factor two to four times greater than the control group in developing breast cancer.